1. Field of the Invention
The present invention relates generally to commercial, refrigerated food display cases of the type commonly found in supermarkets and similar establishments. In a more particular sense, the invention has application to cases of the type described, in which the front of the case is closed by a display window and access to the case is normally had through rear doors. Cases of this type are in widespread use, for marketing service meats, cheeses, or other products that must be sliced or otherwise prepared according to the wishes of the customer, or for marketing other products such as fresh fish or delicatessen items.
In a still more particular sense, the field of the invention may be described as that in which are included devices for preventing the condensation of moisture on the display windows or other transparent surfaces, in food display cases coming within the above stated categories.
2. Description of the Prior Art
The problem of inhibiting, or hopefully completely preventing, the formation of condensate on the surfaces of the display windows of food display cases, has probably existed since cases of this type were first designed. Given a predetermined low temperature and humidity within the case in relation to that in the surrounding ambient, condensation will occur despite various design features and expedients employed to overcome the problem.
It has been proposed, for example, to provide multi-panel display windows, and these have had good results. They have the problem, however, of being very expensive. Further, the display windows of modern cases are almost always hinged so that they may be swung upwardly to facilitate loading or cleaning of the case, or cleaning of the interior surface of the window. Multi-pane windows have not heretofore been liftable because of their great weight, and also because lifting imposes torque on the window, which in turn may break the seal between the panes. This may cause leakage, requiring replacement of the entire window.
Single-pane glass can, of course, be made in any of various attractive, curvilinear forms. Single-pane display windows have, however, the disadvantage that they are particularly subject to condensation problems.
It has been heretofore proposed, to eliminate or inhibit the formation of condensate on the surfaces of display windows of refrigerated display cases, that the interior surface of the window be heated. It has been proposed, for example, to force hot air through spaces occurring between the panes of a flat, multi-pane, display window as disclosed, for example, in Green U.S. Pat. No. 2,257,948. It has also been proposed to circulate hot gas through conduits to heat air in a manner that will cause the heated air to rise immediately adjacent the undersurface of the display window (Jarvis U.S. Pat. No. 2,287,997). Or, as disclosed in U.S. Pat. No. 2,706,387 issued to Swanson, exterior surfaces of display windows have been heated by air passing through a two-part condenser. And, in U.S. Pat. No. 4,325,227 issued to Ibrahim, ambient air is drawn from the exterior of the cabinet through a space between the panes of a multi-pane window. In Ibrahim U.S. Pat. No. 4,361,012 it is again proposed that an ambient air band be passed across the outer surface of the display window, to warm the glass panes slightly so that condensate on the interior glass pane surfaces can be reduced. All of these attacks on the condensation problem share a common deficiency, in that they represent relatively complicated approaches which in some instances are not practical from a manufacturing standpoint, in other instances are not cost-effective, and in still other instances fail to assure minimal formation of condensate on the interior surface of the display window, especially if the window be of the single-pane type.
Further, in the prior art, there has been no suggestion for utilizing a curvilinear window form whereby a heated air flow will travel smoothly, that is, with minimum turbulent effect, along several angularly related interior surfaces of the window, which surfaces are connected by smoothly curved areas, in such a way as to maximize the efficiency of the anti-condensate warm air flow and at the same time provide a window that permits viewing of the product from directly above as well as from the front of the case.